1. Field of the Invention
The present invention relates to a display device and in particular to a transflective type liquid crystal display device disposed with a conductive film on two insulating films.
2. Background Art
In recent years, so-called transflective type liquid crystal display devices disposed with the two display systems of a reflective display and a transmissive display have been heavily used as display units in portable devices, for example.
Transflective type liquid crystal display devices are disposed with a transmissive region and a reflective region in a single pixel. In a transflective type display, a transmissive mode and a reflective mode are mixed. In the transmissive mode, light passes through the transmissive region disposed in the pixel and reaches the eyes of the viewer. In the reflective mode, light is reflected by the reflective region and reaches the eyes of the viewer.
These transflective type liquid crystal display devices are effective when used outdoors and the like. During use in an environment where the surroundings are bright, transflective type liquid crystal display devices perform display in the reflective mode in addition to the transmissive mode and utilize outside light for display.
Transmissive type liquid crystal display devices have the problem that visibility outdoors on a clear day, for example, drops when the outside light is extremely bright. Reflective type liquid crystal display devices have the problem that visibility drops extremely when the outside light is dark.
Transflective type liquid crystal display devices combine the functions of both the reflective type and the transmissive type as means for solving these problems.
In transflective type liquid crystal display devices, an active matrix system using thin film transistors (called “TFTs” below) as switching elements for selectively supplying video signals to pixel electrodes is widely used.
Active matrix liquid crystal display devices include a TFT substrate and a color filter substrate. TFTs and pixel electrodes are formed on the TFT substrate, and color filters for performing color display are disposed on the color filter substrate. The TFT substrate and the color filter substrate are disposed facing each other, and a liquid crystal composition is sealed between these substrates. Plural video signal lines and plural scan lines intersect each other and are disposed on the TFT substrate. The regions partitioned by the video signal lines and the scan lines are called pixel regions. The plural pixel regions are disposed in a matrix. Additionally, a TFT and a pixel electrode are disposed in each pixel region.
In liquid crystal display devices, opposing electrodes are disposed so as to face the pixel electrodes, and electric fields are generated between the pixel electrodes and the opposing electrodes. Display is performed utilizing the phenomenon that the orientation directions of the liquid crystal molecules are changed by these electric fields and the characteristics of the liquid crystal layer with respect to light change in accompaniment therewith.
The vertical electric field system, where the opposing electrodes are disposed on the color filter substrate, and the in-plane switching (IPS) system, where the opposing electrodes are disposed on the TFT substrate, are commonly known.
In transflective type liquid crystal display devices, sometimes an organic resin film is used as an insulating film. With transflective type liquid crystal display devices, it is necessary to halve the thickness of the liquid crystal layer in the reflective regions with respect to the transmissive regions. For that reason, the organic resin film is disposed as a thick interlayer insulating film under the reflective regions with the purpose of making the liquid crystal layer thin.
Further, among transflective type liquid crystal display devices, devices where a retardation layer is disposed in the reflective regions or the transmissive regions are in development. These devices attempt to adjust, with the retardation layer, optical retardations that arise in the reflective regions and the transmissive regions.
Transflective type liquid crystal display devices have been proposed by JP-A-2005-259371 and the like, for example.